This invention relates to an apparatus and method for the transverse folding of webs such as those made into wet wipes, napkins, hankies, or the like. Representative showings of the prior art can be seen in co-owned U.S. Pat. Nos. 1,566,079, 3,489,406, 3,498,600, 3,689,061, 3,870,292, 4,349,185, 4,625,957, 4,682,997, and 4,824,426, and other U.S. Pat. Nos. 5,211,320, 5,795,433, 5,904,277.
The process of producing stacks of transverse folded product usually requires vacuum rolls to hold, transfer, and fold the product. The prior art devices which used vacuum rolls were limited in speed as the vacuum had to be turned on and off at critical times. The vacuum systems are very expensive to manufacture, have very high maintenance costs and downtime, and are often limited in speed as the vacuum system plugs. When wet product is folded, wetting solutions are extracted from the web, which is undesirable and costly. The extracted solutions are difficult to recycle and increase waste.
The prior art vacuum and cutoff rolls were also limited in the products they could run. Cutoff sizes were set by the roll diameters, and running multiple cut lengths required significant change-over of parts and time.
It is desirable to provide a machine which can operate more products and cost less to operate with less waste.
U.S. Pat. No. 3,762,697 describes a folder for a web-fed rotary press. The folder includes folding blade cylinders which include tucking devices which travel in a hypocycloidal path as the cylinders rotate.
U.S. Pat. No. 4,190,242 also describes a tucking device which travels in a hypocycloidal path within a gripping-cylinder. The gripping cylinder includes pins for holding product on the cylinder.
U.S. Pat. No. 5,368,540 describes a hypocycloidal folding device which includes a folding cylinder which carries folding jaws which follow a hypocycloidal path.
The assignee of this invention has sold machines for folding wrapping paper and machines for folding diapers which utilized tuckers which travelled in a hypocycloidal path. However, such machines were not suitable for folding wet wipes and were set up for folding only one product length. The machines were not readily adjustable for folding products of varying lengths.
When the machine for folding wrapping paper was used for folding wet products, the wet produts, and even some dry non-woven products, would stick to the cutoff blades and not drop downwardly. The product also tended to stick to the vertical belts which conveyed the product to the tucker. The product would sometimes follow the belts into the tucking nip and would not be folded.
The invention provides a transverse folding apparatus which is particularly suitable for wet wipes and which eliminates vacuum rolls. The elimination of vacuum systems reduces costs and avoids the limitations of the prior art vacuum systems.
The apparatus uses a pinch cutoff to cut individual product to the desired length, a vertical belt feed system, a horizontal belt system, a hypocycloidal motion tucker for folding the product, and a stacker. The cutoff and anvil rolls include corrugated comb shells which pull the product off of the rolls. One of the sets of vertical belts extends beyond the tucker so that the leading end of the product was conveyed past the tucker. The tucker is notched so that it did not contact the belts.
The hypocycloidal tucker can be used with an infinite range of product lengths, and a variable speed cutoff system varies the product length as desired within a wide range of product sizes.